knocking? pinging?

When people talk about engine knocking or pinging, how are they different from each other?

What is knocking and what is pinging? How do you guys know which is which?

It may sound somewhat stupid, but I just have no idea.

Any help?

Reply to
Me
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Not a stupid question at all.

Pre-ignition "knock" and "ping" are in fact the same thing. It happens when the air/gas mixture ignites in the cylinder on the compression stroke, prior to the spark plug firing, hence "pre-ignition". Usually happens when the engine is hot and under load and the air/gas mixture is too lean. OR that there's not enough EGR (Exhaust Gas Recirculation). The EGR valve (and associated items, like the exhaust differential pressure sensor) work together to eliminate ping/knock - by mixing some exhaust gas with incoming air/gas mix, the ignition temperature is significantly reduced (due to more oxides), thus eliminating ping/knock. Pre-ignition can damage valves, burn up spark plug tips, and in severe prolonged cases, even damage a piston.

It was happening in our explorer quite a bit, until I discovered a defective DPFE sensor (senses the exhaust gas recirc differential pressure). Once replaced, the problem went away.

Mike

Reply to
Mike Mayer

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